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TANNINS AND WOOD PRESERVATION

Objective

The proposed work has two purposes:

to determine and characterize the main European sources of tannins (woods and barks);
to explore their possible use as preservatives for wood or materials derived from wood.

The research proposed has three purpos
es: 1-to understand the mechanisms by
which tannins protect lignocellulose f
rom biodegradation; 2-to determine and
characterise the main European source
s or materialsplore their possible use
was preservatives for wood These thre
e objectives are motivated by the foll
owing observations: 1-Heartwoods rich
in tannins (e.g. oak or chestnut) are
naturally durable. The mechanisms by w
hich tannins protect lignocellulose ar
e unknown even if several hypotheses h
ave been proposed. A better understand
ing of these mechanisms will allow to
make a rational choice among the diffe
rent sources of tannins and to modify
these tannins in order to obtain an op
timum fungicide activity.
rich in tannins (10 to 30% of dry matt
er). Oak and chestnut woods are curren
tly extracted for their tannins, mainl
y for leather production. Tannins from
oak bark were used on a large scale u
p to the beginning of this century. A
renewed interest for natural organic c
hemicals (and tannins) has emerged aft
er oil shortages in the 1970's. Resour
ces should thus be reexamined in the l
ight of new potential uses of tannins.
3-One of these potential uses is relat
ed to (ligno)cellulose preservation. T
raditionnally, tannins heve been utili
sed as preservatives for fish-nets, ro
pes and fabrics. Very good protection
of wood has been recently obtained in
North-America, by impregnation with ta
nnins and Cu (II) salts. Due to their
physico-chemical properties (and parti
cularly their astringency), tannins ca
n be used not only for their fungicide
properties but also to fix within the
wood or materials derived from it, ot
her fungicides or insecticides otherwi
se easily leached. Wood adhesives base
d on tannins have been used in a few c
ountries, but have not been studied so
far in relation to durability improve
ment of the product. Different tannin
extracts, alone or in combination with
other fungicides or insecticides, wil
l thus be tested for impregnation of w
ood and manufacture of particleboard a
nd plywood.
The properties of the products, includ
ing the resistance against rots, bluestains and termites for woods and agai
nst rots for wood panels, will be eval
uated.
Such a research associating tannins an
d wood preservation has not yet been d
eveloped in Europe. The gathering of 8
laboratories covering fields such as
tannin chemistry, polyphenol microbiol
ogy, wood preservation and wood panels
making, should lead to the developmen
t of new durable and environmentally s
afe products based on wood.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Institut National de la Recherche Agronomique (INRA)
Address
Route De Thiverval
78850 Thiverval-grignon
France

Participants (5)

Centre Technique de l'Industrie du Bois
Belgium
Address
830,Chaussée D'alsemberg
1180 Bruxelles
Centre Technique du Bois et de l'Ameublement (CTBA)
France
Address
10 Avenue De Saint-mandé
75012 Paris
ECOLE NORMALE SUPERIEURE
France
Address
Rue Lhomond 24
75231 Paris
Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria
Spain
Address
Km.7,carretera De La Coruña-apdo. 8.111
28040 Madrid
Isoroy SA
France
Address
108 Route D'orbec
14102 Lisieux